... Non-indigenous marine species often change the abundance and diversity of native species in coastal ecosystems. On the SW Atlantic coast, the macroalgae Ahnfeltiopsis sp. (Rhodophyta, Phyllophoraceae) and Schizymenia dubyi (Rhodophyta, Schizymeniaceae) have invaded the intertidal rocky shore of Mar del Plata, Argentina (38°S, 57°W). To study the spread and ecological associations of these invasive ...